Magnetic compass repeater



Patented Nov. 7, 1944 UNITED STATES PATENT OFFICE MAGNETIC coMPAss Barnum James Moses smith, United smeg Navy Application June 4, 1943, Serial No. 489,865 I (ci. ca -226) (Granted under the m er Maren s, im, u .mended April-so, 192s; s'zo o. n.151)

3 Claims.

This invention relates to a magnetic compass repeater and has for an, object to provide an improved system for operating compass repeaters from a magnetic compass, being especially inthe compass card I! is a stationarysupporting ring it which also acts as a bearing for an azimuth ring gear 20. This ring gear 20 is provided with beveled teeth 2i which are meshed with the teeth of a beveled gear 22 keyed on a shaft 23. Also supported by the stationary ring i8 are three pairs of electrical ring conductors 24, 25, and 26.

tlcer, and other stations where the repeater compasses are located are no longer available. It is an object of this invention to provide a means for connecting a Amagnetic compass to the gyro repeater compasses so that the gyro repeater compasses will then follow the magnetic compass at all the repeater compass stations.

A further object of this invention is to provide a means for so connecting a magnetic compass to acompass repeater system that there will be no frictional or mechanical drag aiecting the compass card but which will leave the compass card free to operate under the magnetic pull of the polar neld without any mechanically added errors or lags.

With the foregoing and other objects in view. the invention consists in the construction. combination and arrangement of parts hereinafter described and illustrated in the drawing in which:

Figure 1 is a schematic outline of the invention utilizing a block diagram.

Figure 2 is a fragmentary plan view of the compass card prisms and cells.

There is shown at I0 a standard magnetic compass card mounted in any conventional manner so that it may rotate freely about its .center pivot point Il on a. shaft I2. This compass card l0 is free to rotate and take its position under the inuence of the polar iields. At I4 there is shown one o! a series of repeater compass cards. This compass card I3 may be the compass card of one of the regular gyro repeater compasses located at various stations throughout the ship or vehicle and is ordinarily connected to the gyro compass of the ship. However, if and when the gyro compass ofthe ship should become inoperative, then it is the essence of this invention that the same gyro repeater compasses may be connected to and operated by a standard magnetic compass card l0 which is connected to the various repeater compasses by thesystem herein disclosed. l

Mounted adjacent one edge of the compass card i0 is a double prism support I5 carrying two prisms i6 and il. Concentrical with and above Depending from the azimuth ring gear 20 is an electric light 21 for projecting a beam of light 2l so that it will strike the doull e pri sms l il.

Th li ht 21 is so supported on the ring gear zo with-EM a i'te the compass card in that it is at the same radial distance from the pivot point il of the compass card l0 that the double prismSJLgnd i.l. `are from this same pivot point ii. Also depending from the ring gear 20 on the opposite sides of the light 2] are two photo electric cells M and 3|. These cells-Tam and the light source 2 eing all mounted on the same ring ge are movable when the ring shaft 20 moves, but on the other hand, the photo electric cells 20 and 2l and the light source 21 are stationary relative to each other.

They are so mounted with relation to the double prisms i6 and il that when the light source 21 is directly over the dgublelrismjandg, the beam from the light source 21 is split into two beams 32 and 23, beam 32 being reiiected by the prism I1 to the photo electric cell 3|. Electric light 21 receives its current by means of leads 34 connected to electric brushes 35 mounted on a brush support 3B also carried by the ring gear 20. The electric brushes I5 are in contact with the pair of ring conductors 24 which in turn are connected by leads 31 to a suitablesource of elec trical power.

Photo electric cell 30 is connected by leads 28 through brushes 40 to the pair 25 of ring conductors which in turn are provided with electrical leads 4I to the amplifier shown in block diagram at 42. The brushes 4i! are mounted on bracket 4l depending from ring gear 20. The other photo electric cell 2i is similarly connected by leads 44 through brushes 45 and pair 26 ofl ring conductors to leads 4B to the amplifier 4l, the brushes 45 being also mounted on a bracket 48 depending from ring gear 20.

The amplifier 42 is connected liy leads 50 to a solenoid 5l for attracting one armature 52 of a balanced switch arm 5I which includes an insulated section 54 and is pivoted as at v55. 'Ihe @Ross REFERENCE B2 and It, thus keeping the switch 53 in balanced position However, when the compass card i rotates in either direction, it will, through the prism support I5, move one or the other prisms I6 and l1 out of the beam 2l thus immediately diminishing or eliminating one or the other of the split beams 32 or 33. Assuming that it has moved clockwise, beam 32 would be diminished or climinated so that photoelectric cell 3i alone will be actuated. This will cause this ampliner l1 to actuate the solenoid Il and attract the armature 58, thereby causing the back of the armature 52 to close the contacts 60. Contacts 80 are connected through leads I2 to`one side of servomotor the magnetic compass card il at the same time allowing for any magnetic compass error. Then the crank Il is operated to cause the gear Il to reengage both gears I3 and 1I and the D. C. power supply li is connected to the servomotor I3 by moving the switch 3l to closed position Il'.

The repeater compass cards will now be in position to follow all the movements o! the magnetic compass card Il, for as the magnetic compass card il rotates in either direction, it will diuiin ish or break one or the other of the light beams 32 or 33 to the photo electric cells 3|! or 3l, as already described, thus vunbalancing the switch 53, and through servomotor 83 it will operate the self-synchronous transmitter 12 to cause the repeater compasses il to follow the movement of the compass card il. Simultaneously through the gear train, it will cause the ring gear 2l to follow the movement of the compass card i0 and `catch up to it when it stops with the beam 28 again split into two equal beams 22 and 33.

'thus stopping the operation of the servomotor 63 which receives its power from a D. C. power supply t! through a switch Il and is provided with a shaft t5 carrying a gear I6. With the switch 64 in the closed position i4', closing of the contacts il will, through the servomotor 63, cause the gear 83 to rotate in one direction. On the other hand the gear 86 will be rotated in the opposite direction if the compass card i0 rotates counter-clockwise as such movement will cause the closing of contacts li connected byleads 31 to the opposite side of the same servomotor 63 to thus cause it to rotate in the opposite direction.

The gear 0I is meshed with a gear 68 on a shaft l0 having a crank handle 09 and connected by a sleeve coupling within a self-synchronous transmitter 12 so that the gear 63 may be enmeshed with or disengaged from the gear 66. Another gear 1I in the same plane with the gear it is also in mesh with the gear 63 when the gear I8 is in mesh with the gear i6.

This gear 1| is mounted on a shaft 12 connected by means of a universal Joint 13 through a train of shafts 1l and universal joints 15 to the shaft 23 which carries the beveled gear 22 meshed to the teeth 2i of the azimuth ring gear 20. The self-synchronous transmitter 12 is connected by leads 1l to each of the repeater compasses il and stopping the movement of the repeater com- Pass cards.

Other modifications and changes in the number and arrangement of the parts may be made by those skilled in the art without departing from the nature of the invention, within the scope of what is hereinafter claimed.

that it is desired to operate. These repeater compasses Il are preferably the same repeater compasses that are connected to the gyro compass of the ship or vehicle. A 110 volt, 60 cycle stator power supply 11 is connected by leads 18 through the switch III to the stator of the self-synchronous the gear 68 in mesh with gear 1i thus causing.,

through the train of shafts 14 and universal joints 15, the shaft 23 through gear 22 to rotate ring rgear 20 until the light beam 28 is exactly split by the double prisms Il and I1 into the two beams 32 and 33. The crank handle 68 isthen operated to slide the shaft 1l in its sleevel coupling until The invention described herein may be manu; factured and used by and for the Government of the United States of America for governmental purpos withoeut the payment of any royalties thereon or therefor.

What is claimed is:

1. A follow up for a magnetic compass having a card comprising a double prism Support. said double prism support being mounted on said compass card, double prism means carried by said support, a light source directing a light beam at said double prism means, said double prism means dividing said light beam into two separated light beams, a pair oi' photo electric cells, one of said photo cells being in the path ofone of said divided light beamsand the other of said photo 'electric cells being in the path of the other of said divided light beams, and means controlled by differential energization of said photo electric cells when the light beam to one of said photo electric cells is diminished or discontinued by the bmovement of the double prism support on said -vided light beams and the other of said photo electric cells being in the path of the other of said divided light beams, and means controlled' v by differential energization of said photo electric the gear 88 is disengaged from both gears ll and 1|.

Then after placing switch 80 in closed position 80'. the crank 39 is rotated to make the compass cells when the light beam to one o! said photo electric cells is diminished or discontinued by the movement of the double prism support on said compass card to cause said light source to move correspondingly, movable supporting means for supporting said light source and said pair of photo electric cells in fixed relation to each other thereon, and actuating means causing said movable supporting means t0 che said double prism support as long as it is moving and to stop when it caught up with said double prism support.

3. A follow up for a magnetic compass having a card comprising a double prism support. means for keeping said double prism support in a dennite relation to the polar fields, double prism 4 means carried by said support, a light source directing a light beam at said double prism means. said double prism means dividing said light beam into two separated light beams, a pair of photo electric cells, one of said photo cells being in the JAMES MOSES SMITH'.

rr. f 

